Ink jet imaging devices produce text and images on a substrate, such as paper, by ejecting minute quantities of ink from a reservoir onto the substrate in response to electrical commands. The electrical commands activate small orifices or ink jets in a print head to eject the ink in the desired locations to form the desired images. Because the ink in an ink jet imaging device is used up eventually in the printing process, conventional ink jet imaging devices include the ink reservoir in a replaceable cartridge commonly referred to as an ink jet cartridge. The print head containing the orifices through which the ink is ejected is also commonly included in the replaceable ink jet cartridge. The remainder of the ink jet imaging device includes electrical control components and mechanical components for moving the ink jet cartridge with respect to the printing substrate (paper) and for moving the substrate with respect to the ink jet cartridge.
Photocopiers, printers, plotters, and facsimile machines are examples of devices that may utilize an ink jet printing or imaging process. As used in this disclosure “ink jet device” encompasses any type of device using an ink jet process. Also, for purposes of the following description, the portion of the ink jet device other than the ink jet cartridge will be referred to herein simply as an ink jet device whether or not the ink jet cartridge is installed. The portion of the ink jet device that carries the consumable ink for the ink jet imaging process will be referred to as an ink jet cartridge, or simply cartridge, regardless of the particular design and regardless of the other components included on the ink jet device such as a print head and associated electrical lines and contacts.
FIG. 1 is a view in perspective of a typical prior art ink jet cartridge 100. Ink jet cartridge 100 includes a container 101 adapted to contain a supply of ink (the ink not being shown in the figure). The bulk of container 101 is generally rectangular in shape with a lower portion 102 projecting from the rest of the container. Print head assembly 104 is located on lower portion 102 of container 101 and includes a large number of minute, electrically stimulated orifices or ink jets 105 through which ink from container 101 is ejected in the printing process. It will be appreciated that the orifices or ink jets are shown diagrammatically in FIG. 1 in an exaggerated scale, and that the orifices are in fact very small in order to produce the desired image resolution. The commands or electrical stimuli required to operate the orifices or ink jets 105 are applied to print head assembly 104 through electrical conductors 106 which terminate at contact pads 107 on a side of container 101. An ink jet device in which cartridge 100 is to be used will include a corresponding set of electrical contacts exposed so as to make contact with contact pads 107 on the cartridge. The electrical signals required for operating print head assembly 104 originate from a print control system (not shown) included in the ink jet device. The illustrated prior art ink jet cartridge 100 also includes additional orifices facilitating fluid communication to ink container 101. The first additional orifice comprises an opening 109 commonly referred to as a vent opening or vent hole. The second additional orifice comprises an opening which is commonly referred to as a maze opening or maze hole located on the surface of cartridge 100 indicated by arrow 110. The maze hole is associated with a ball that functions as a check valve to prevent the flow of material out of container 101.
Due to space limitations and other physical restrictions in ink jet devices, ink jet cartridges typically have a relatively limited supply of ink for use in the ink jet printing process. The working life of the print head assembly of an ink jet cartridge is, in fact, commonly much greater than the working life of the ink supply in the cartridge. Thus, although original equipment manufacturers may prefer for ink jet device users to use totally new ink jet cartridges due to the relatively high profit margins associated with selling new ink jet cartridges, it is commonly possible to refurbish and reuse ink jet cartridges many times before they are no longer serviceable. Due to the popularity and low cost of ink jet devices, the sale of both new and used ink jet print cartridges has become a very big business.